An organic light-emitting device is an emissive device that has advantages in that it has a wide viewing angle, excellent contrast, and a rapid response time, shows excellent characteristics such as brightness, driving voltage, and response speed, and becomes polychromatic.
A typical organic light-emitting device may include an anode, a cathode, and an organic layer sandwiched between the anode and the cathode. The organic layer may include an electron injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode. When a voltage is applied between the anode and the cathode, holes injected from the anode move to the light emitting layer via the hole transport layer, and electrons injected from the cathode move to the light emitting layer via the electron transport layer. Carriers such as the holes and the electrons are recombined in a portion of the light emitting layer to generate excitons. In this case, light is emitted as the excitons radiatively decay from an excited state to a ground state.
Meanwhile, at this point of time at which there is an increasing interest in new renewable energy all over the world, organic solar cells having possibilities and various advantages as future energy sources have come into the spotlight. The organic solar cells may be produced at small thickness and low manufacturing costs, compared to the inorganic solar cells using silicon, and thus may be widely applied to various flexible devices in the future.
There is a demand for development of conductive thin films which allow easy film formation while satisfying a work function, conductivity, and the like, which are required for the separate electronic elements such as the organic light-emitting devices, and the organic solar cells. Such conductive thin films can be used as layers configured to compensate for a low work function (4.6 to 4.9 eV) of indium tin oxide (ITO) to improve hole injection or extraction for conventional transparent metal oxide electrodes (i.e., ITO electrodes), and can also be independently used as transparent electrodes instead of the metal oxide electrodes. In particular, since the price of ITO electrodes continues to increase due to the issues regarding to the exhaustion of indium resources, research on materials replacing the indium resources has been urgently required. For this reason, although different types of materials for transparent electrodes replacing the materials for conventional ITO transparent electrodes have been developed, the materials for transparent electrodes having a satisfactory work function remain to be found. Also, since the conventional ITO transparent electrodes tend to be easily broken due to their mechanical instability when they are bent, it is difficult to apply them to flexible electronic elements. Accordingly, there is a demand for development of transparent flexible electrodes.